The invention relates to a gondola lift or chairlift having a device for driving cars or chairs in stations or terminals. In such a lift, an aerial cable runs continuously in a closed circuit and the chairs are detached from the cable as they enter the station and travel through the station on a half-loop circuit, linking up and down tracks, before being reattached to the cable as they leave the station. As used herein, the expressions chairlifts and chairs shall respectively include gondola-lifts, cars, gondolas and similar apparatuses. The chairs are fixed by a hanger arm to a carriage bearing a grip for coupling the chair to the cable. The hanger arm includes rollers for running on a transfer rail extending in a half-loop circuit in the stations. The grip is of the detachable type permitting uncoupling of the carriage from the cable in the stations and the running of the carriage on a transfer guiding rail at a slow speed. Braking or deceleration, acceleration, and the driving of the uncoupled grip carriage in the stations may be provided by wheels or sheaves frictionally acting on a running friction plate rigidly secured to the grip carriage body. At least on the acceleration and/or deceleration sections, a battery or set of friction drive sheaves are staggered along the travel circuit in the station to cooperate with the friction plate. Immediately neighboring friction sheaves possess different circumferential velocities in order to stepwise decelerate or accelerate the chairs. The length of the friction plate is longer than the spacing or distance between two successive friction sheaves so that a carriage is always controlled by at least one friction sheave. Such a friction drive device is currently used for driving on the one hand the chairs detached from the cable through the station at a reduced speed and on the other hand for braking the carriage bearing these chairs at the entry to the station and for accelerating the carriages to synchronize the speeds of the carriages and of the cable before recoupling at the station exit. The drive sheaves dispose on the reduced speed sections of the circuit are driven in rotation by a motor at an equally reduced speed and the drive plate comes into contact with the following drive sheave smoothly, since the tangential speed of that sheave is equal to the speed of the drive plate. On the deceleration section the first sheave is driven at the speed of the cable whereas the speeds of the following sheaves are stepwise lower to decelerate the carriage. The front edge of the drive plate engages the following sheave while its rear edge is still engaged by the former sheave running at a greater speed and there results from the simultaneous engagement of two friction sheaves with the friction plate a pronounced wear. On the acceleration section the drive plate is in the same way engaged by sheaves running at different speeds. A driving device of this kind is for example described in the U.S. Pat. No. 4,563,955.
A chairlift which eliminates this drawback is known from the U.S. Pat. No. 4,794,864. In this prior art chairlift a spring is inserted between the friction sheave and its axis but such a device is quite complicated and expensive and does not prevent some jerk.
The object of the present invention is to provide a correct circulation of the carriages in the station. Another object is to effectively reduce the frictional wear of the sheaves, for instance constructed as pneumatic wheels or tires.